1. Field of the Invention
The invention relates generally to the field of radio communication and, in particular, to a system and method of increasing the range of a data link without increasing transmit antenna size, receive antenna size or transmit power.
2. Description of the Related Art
Multipath fading limits the effective size and thus gain of a receive antenna or phased array. The fading can be time varying in phase modulation, amplitude modulation, and time delay so that fixed combining is not applicable. Data link range in fading conditions are limited by transmit power, transmit antenna gain and receive antenna gain. Transmit power and antenna gains are often limited by the platform limitations.
The receive antenna gain is normally considered to be a function of the size of the antenna or array. If 3 dB additional gain is necessary, the antenna is doubled in size or twice as many array elements are used. In the case of a multipath environment, whether troposphere refraction or signal reflection from a conducting surface, the data link is limited more by the fading of the channel rather than by the actual array gain. Data link performance is thus limited by the fading multipath environment. The multipath causes distortions that differ at each element so that the array no longer sees a plane wave arrival of the desired signal.
A need therefore exists for a communication system and associated method improving detection range without increasing transmit power or transmit antenna size.